Twin-Twin Transfusion Syndrome (TTTS)
What Is Twin-Twin Transfusion Syndrome?
Twin-twin transfusion syndrome (TTTS) is a rare, serious condition that can occur in pregnancies when identical twins share a placenta. Abnormal blood vessel connections form in the placenta and allow blood to flow unevenly between the babies. One twin − called the donor – becomes dehydrated; and the other − called the recipient − develops high blood pressure and produces too much urine and over fills the amniotic sac.
TTTS is a disease of the placenta, not the babies themselves, and affects each twin differently. The donor twin, who is becoming dehydrated, does not produce as much urine as it should, resulting in a low amount of amniotic fluid and poor fetal growth. The recipient twin, whose system is overwhelmed by too much fluid, produces more urine than usual. This eventually leads to an enlarged bladder and excess amniotic fluid. The excess fluid can put a strain on the recipient twin’s heart, sometimes leading to heart failure.
Without treatment, this condition can be fatal for both twins. Fetal surgery is sometimes necessary to save one or both babies. The prognosis is usually better when the condition develops after 20 weeks’ gestation.
Evaluation & Diagnosis of TTTS
The first step is to confirm that their symptoms are related to TTTS and not to another condition, such as diabetes or a viral infection. We use ultrasound, fetal MRI and fetal echocardiography (a detailed examination of the baby’s heart by ultrasound) to provide more information about the severity of the condition and to help us recommend a treatment plan once TTTS is confirmed.
Staging Twin-Twin Transfusion Syndrome
Our team uses the Quintero staging system to stage TTTS on a scale of one to five, five being the most serious.
Stage I: Significant difference in amniotic fluid volume in each twin’s sac
Stage II: Inability to see the smaller baby’s bladder by ultrasound
Stage III: Abnormal blood flow through the umbilical cord or fetal vessels around the heart
Stage IV: An abnormal fluid accumulation in more than one body cavity, also known as hydrops. This can be present in one or both twins.
Stage V: The death of one or both twins
TTTS Treatment Options
The treatment plan we recommend depends on the severity of the condition and how advanced the pregnancy is.
1- Expectant Management (Monitoring the Pregnancy)
In less severe cases, surgery may not be needed. In that event, we will use ultrasound and fetal echocardiography to monitor the babies during the pregnancy. If their condition worsens, our team will work with the patient, her family and her referring physician to decide what treatment is best. Sometimes, early delivery is the best option.
2- Amnioreduction (Draining Excess Amniotic Fluid)
When babies are only mildly affected by TTTS, we may recommend amnioreduction to drain the excess amniotic fluid from the recipient twin’s sac, which may improve blood flow. If amnioreduction is not effective, patients may be given the option to proceed with selective fetoscopic laser photocoagulation (SFLP), more commonly known as laser surgery.
3- Selective Fetoscopic Laser Photocoagulation (Laser Surgery)
When babies are more severely affected by TTTS, the team may recommend selective fetoscopic laser photocoagulation, or laser surgery. This procedure involves making a small incision in the mother’s abdomen and inserting a trocar, or small metal tube, into the uterus. The surgeon then passes a fetoscope (a kind of medical telescope) through the metal tube in order to see all of the blood vessel connections on the surface of the placenta shared by the twins.
After all of the abnormal blood vessel connections are identified, the laser is applied to seal shut these vessels and disconnect them permanently. Afterward, the surgeon drains excess amniotic fluid through the previously placed trocar. Surgery is then complete.
The location of the placenta will help determine the type of anesthesia used for the laser surgery. If the placenta is “posterior,” or located on the back wall of the uterus, we may recommend intravenous (IV) sedation and a local anesthetic. However, if the placenta is “anterior,” or located on the front wall of the uterus, we recommend intravenous sedation, a local anesthetic and possibly an epidural.
After laser surgery, the majority of patients remain in the hospital for one day until their condition stabilizes. Post-operative ultrasound and fetal echocardiography are then repeated about five days after the laser surgery to reassess the fetal condition. We will work with the patients’ maternal-fetal medicine specialist and obstetrician to ensure proper follow up once they return home.
Long Term Prognosis for TTTS
Twin-twin transfusion syndrome often causes premature birth, even when treated successfully. In this case, babies require care in a neonatal intensive care unit.
The majority of babies who are successfully treated for twin-twin transfusion syndrome live normal, healthy lives. However, some experience mild symptoms, such as anemia, which are easily treated. Other, more serious problems include brain lesions, neurologic deficits and heart failure. specialists can help by providing long-term, expert care for these children.
We are honored to be one of the few centers that treat these rare case internationally and in our region . We would like to reassure our patients these cases are easy to treat and with good success rate .
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